Background. The ReproQuestionnaire (ReproQ) measures the client's experience with maternity care, following the WHO responsiveness model. In 2015, the ReproQ was appointed as national client experience questionnaire and will be added to the national list of indicators in maternity care. For using the ReproQ in quality improvement, the questionnaire should ... read more be able to identify best and worst practices. To achieve this, ReproQ should be reliable and able to identify relevant differences. Methods and Findings. We sent questionnaires to 17,867 women six weeks after labor (response 32%). Additionally, we invited 915 women for the retest (response 29%). Next we determined the test-retest reliability, the Minimally Important Difference (MID) and six known group comparisons, using two scorings methods: the percentage women with at least one negative experience and the mean score. The reliability for the percentage negative experience and mean score was both 'good' (Absolute agreement = 79%; intraclass correlation coefficient = 0.78). The MID was 11% for the percentage negative and 0.15 for the mean score. Application of the MIDs revealed relevant differences in women's experience with regard to professional continuity, setting continuity and having travel time. Conclusions. The measurement characteristics of the ReproQ support its use in quality improvement cycle. Test-retest reliability was good, and the observed minimal important difference allows for discrimination of good and poor performers, also at the level of specific features of performance. show less